The present invention relates to a high strength ball end for a link such as a hitch link for a three-point hitch.
A typical center link for a 3-point hitch includes ends in which a spherical bushing, or ball, is held captive within a socket. The ball has a central bore so that it can be coupled by a pin to either a tractor bracket or to an implement coupler. During normal operation, the ball rotates within the socket and can wear. If the wear progresses to the point where an undesirable amount of clearance exists between the ball and socket, then the ball or the entire end must be replaced.
In many ball end designs, this is not easily done, or possible. Many link ends have a ball that is installed in the socket and then the end is swaged or crimped down over part of the ball to capture it. The ball in this type of link cannot be replaced because the material of the end must be deformed significantly to remove the ball and may crack if this is attempted.
Another common ball end design uses a pressed-in retainer which captures the ball in the end. This design permits ball replacement if the proper equipment is available to remove the retainer and reinstall it. But often, the retainer is locked in place by crimping the end over it, which then prevents replacement of the ball. It would be desirable to have a link end design which permits replacement of only the ball, instead of a design which requires replacement of the entire link end.
A link end with a removable ball assembly is described in U.S. Pat. No. 6,520,682, issued to Deere & Company. In this design the ball is a two-piece ball and sleeve assembly. The sleeve prevents the ball from rotating to the position where it can be removed through the slot. When it becomes necessary to remove the ball, the sleeve is first removed from a bore through the ball and then the ball is rotated 90 degrees and removed through the slot in the link end. However, this design requires a two-piece ball and sleeve assembly, and thus requires that both parts be machined and hardened at additional cost. Also, in this design both the ball and sleeve must be relatively thin in cross-section. This makes them prone to high. stresses and reduced life, and the ball and sleeve may crack and/or break before they wear out.